Encapsulated flavorings having a particularly long shelf life are produced in the flavoring industry generally by emulsifying the flavoring in molten carbohydrate mixtures with subsequent shaping. Within an extruder for example, an emulsified flavoring is added to the carbohydrate melt and is then extruded through a perforated plate into a previously charged cooled isopropanol bath. U.S. Pat. Nos. 4,707,367; 4,499,112; 3,704,137; 3,041,180; 2,809,895 describe processes of encapsulating flavorings that use such a solvent bath. In the isopropanol bath, the strands are comminuted during the solidification by an agitator to particle sizes between about 0.3 and 1.5 mm. This solvent bath serves to wash the flavoring contents, which adhere to the particle surface of the resultant particles. The encapsulated flavorings are then dried to remove the remaining solvent by centrifugation and gentle vacuum drying.
The sugar residues must be removed by fine filtration from the solvent used for washing. Water and flavoring residues are recovered by distillation, for recycling. Despite these downstream operations, contaminated solvents must be temporarily stored in separate tanks. The entire production process must comply with a high safety standard. The plant must be made explosion-proof and the flexibility with respect to product change is very restricted because of the problems of contamination.
Disadvantages of these solvent bath processes are due to the complex solvent treatment. Additionally problematic, the resulting particles have a low glass transition temperature and therefore readily form lumps.
By using an extruder and solidification in air, shaped strands can also be produced without using a solvent. This procedure is disclosed in U.S. Pat. Nos. 5,603,971; 5,601,865; 5,087,461; 5,786,017; 5,009,900; 4,820,534 and European Patents WO 94/06308; WO 94/23593. Shaped strands arc cooled via a cooling belt or the like. The comminution must be carried out in a downstream mechanical comminution process such as a pelletizer or crusher. During the comminution to the desired particle size between about 0.3 and 1.5 mm, the surface structure of the particles is damaged or destroyed. As a result of mechanical comminution, the surface of the encapsulated particles exposes the flavorings. An increased loading with surface flavorings is disadvantageously connected with this. In addition, an undesirably high fine dust content is formed.
The exposed flavoring on the surface of the particles forms an oily layer on the surface of the particle. This oily layer on the surface causes a marked impairment in the shelf life of the particles.
Therefore, a method to produce flavorings encapsulated in carbohydrates is sought. There is a need for a solvent-free continuous procedure, which involves the integration of the individual steps shaping, cooling, comminution, and dedusting. The particles produced by this sought method must be free from an oily layer from the flavoring used and have a high glass transition temperature. It is desirable for the resulting encapsulated flavorings to have a long shelf life and a high glass transition temperature.